Four alternative tillage systems were compared to a
conventional system at The University of Arizona Agricultural Centers
in Marana and Yuma. The alternative tillage systems offer significant
savings in energy, time, and cost. None of the reduced tillage systems
were associated with a reduction in cotton yield.

Introduction

Cotton growers in Arizona know that their profitability
and survival depend on maintaining high production while minimizing
costs. Tillage operations consume about half of the entire seasonal
energy budget before the seed is planted. In addition, tillage operations
can contribute significantly to soil compaction and dust emissions,
resulting in reduced yield and degradation of the environment.

The purpose of this research was to identify alternative
tillage methods for cotton; and to document tillage operational data,
energy use, time requirements, operating costs and cotton yields over
several seasons.

Reduced tillage systems, tested over several years by
The University of Arizona, offer energy savings and reduced dust emissions
because they are less intensive than conventional systems. Reduced tillage
systems are associated with reduced soil compaction, especially when
they restrict wheel traffic to set paths in the field, a system known
as controlled traffic farming. Reduced tillage systems also reduce field
work time requirements because they require fewer passes over the field.

Materials and Methods

The four alternative tillage systems that were compared
to a conventional tillage system at The University of Arizona were:

Uprooter-Shredder-Mulcher (USM), developed by S. Ben-Dor Automotive
Industries. Ltd. of Israel. This is a two-row machine which uproots
the stalks with counter-rotating pinch tires, shreds the stalks in
a shearbar shredder, and then injects the residue into the soil at
the rear of the machine.

Sundance System developed by Sundance Farms of Coolidge, AZ. Developed
for buried drip irrigation systems, it consists of a ground-powered
stalk puller followed by the Sundance disk which mixes the residue
into the soil and re-lists the beds.

Stalk Puller System developed by The University of Arizona as a
method of harvesting the cotton stalks as a biomass fuel feedstock.
The stalk puller is similar to the "tyre pullers" used to
uproot whole cotton plants in Australia. It is a three-point hitch
mounted implement; each row consists of an undercutting blade which
severs the cotton tap roots, followed by a pair of hydraulically powered
pneumatic pinch tires which uproot the whole cotton stalks. This pulling
action, combined with the forward movement of the machine, causes
the stalks to be thrown upward and toward the rear of the implement,
where they are funneled through a pair of shields to form a windrow.
The stalks are then baled with a round baler and are removed from
the field. Since the specific energy of cotton stalks compares favorably
to that of wood, this has been investigated as a possible source of
energy.

Modified Conventional System; consisting of stalk shredding, disking
with a conventional tandem disk, and rip/listing with a Sundance disk.

Table 1 describes the five systems studied and
includes the operational processes and implements used for each

Results and Discussion

Table 2 lists the number of operations, energy
requirements, time requirements, dust emissions, operating costs and
yield for the alternative and conventional tillage systems. These data
were collected from 1987-1994 at The University of Arizona Agricultural
Centers in Marana and Yuma. All of the alternative tillage systems required
less energy than the conventional. Time requirements were also less
for all alternative tillage systems. Although dust emissions averaged
highest for the Sundance System, there were no statistically significant
differences between tillage systems. This is partly due to the high
dust emissions of the power mulcher used in all tillage systems; this
tended to mask the differences in dust emissions from other implements.
Operating costs were lower for all of the alternative tillage systems.
Although cotton yields with all of the alternative tillage systems averaged
higher than with conventional tillage, these differences were not statistically
significant.

This project has been funded by the Arizona Department of Environmental
Quality's Air Quality Fund. Machinery was donated by Arizona Drip Systems
and Central Machinery Company. Machinery was loaned by Automotive Industries,
Ltd., Bob and Dean Wells of Casa Grande, the LDS Church Farm of Marana,
and Tom Clark Farms of Marana.

Table 1. Tillage systems tested at the
University of Arizona Agricultural Centers in Marana and Yuma.

Issued in furtherance of Cooperative Extension work, acts
of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture,
James A. Christenson, Director Cooperative Extension, College of Agriculture
and Life Sciences, The University of Arizona.

The University of Arizona is an equal opportunity, affirmative
action institution. The University does not discriminate on the basis of race,
color, religion, sex, national origin, age, disability, veteran status, or sexual
orientation in its programs and activities.

Any products, services, or organizations that are
mentioned, shown, or indirectly implied in this web document do not imply
endorsement by The University of Arizona.

Information provided by:Wayne E. Coates wcoates@u.arizona.edu,
Research Professor, Arid Lands
Gary W. Thacker
College of Agriculture and Life Sciences, The University of Arizona
Material written 1996.